MCP73855T-I/ML 查看數據表（PDF） - Microchip Technology
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MCP73855T-I/ML Datasheet PDF : 32 Pages
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MCP73853/55
5.1.6
BATTERY VOLTAGE SENSE (VBAT3)
The MCP73853 monitors the battery voltage at the
VBAT3 pin. This input is tied directly to the positive
terminal of the battery pack.
5.1.7 BATTERY CHARGE CONTROL
OUTPUT (VBAT1, VBAT2)
The battery charge control output is the drain terminal of
an internal P-channel MOSFET. The MCP7385X
devices provide constant-current and constant-voltage
regulation to the battery pack by controlling this
MOSFET in the linear region. The battery charge
control output should be connected to the positive
terminal of the battery pack.
5.2 Digital Circuitry
5.2.1
CHARGE STATUS OUTPUTS
(STAT1, STAT2)
Two status outputs provide information on the state of
charge for the MCP73853. One status output provides
information on the state of charge for the MCP73855.
The current-limited, open-drain outputs can be used to
illuminate external LEDs. Optionally, a pull-up resistor
can be used on the output for communication with a
host microcontroller. Table 5-1 and Table 5-2 summa-
rize the state of the status outputs during a charge
cycle for the MCP73853 and MCP73855, respectively.
TABLE 5-1: STATUS OUTPUTS – MCP73853
CHARGE
CYCLE STATE
STAT1
STAT2
Qualification
OFF
OFF
Preconditioning
ON
OFF
Constant-
ON
OFF
current Fast
Charge
Constant-
voltage
ON
OFF
Charge
Complete
Flashing (1 Hz,
OFF
50% duty cycle)
Fault
OFF
ON
THERM Invalid
OFF
Flashing (1 Hz,
50% duty cycle)
Disabled -
OFF
OFF
Sleep mode
Input Voltage
OFF
OFF
Disconnected
Note:
OFF state: open-drain is high-impedance;
ON state: open-drain can sink current,
typically 7 mA; FLASHING: toggles
between OFF and ON states.
TABLE 5-2: STATUS OUTPUT – MCP73855
CHARGE CYCLE STATE
STAT1
Qualification
OFF
Preconditioning
ON
Constant Current Fast Charge
ON
Constant Voltage
ON
Charge Complete
OFF
Fault
Flashing (1Hz,
50% duty cycle)
THERM Invalid
Flashing (1Hz,
50% duty cycle)
Disabled - Sleep mode
OFF
Input Voltage Disconnected
OFF
Note:
OFF state: open-drain is high impedance;
ON state: open-drain can sink current, typ-
ically 7 mA; FLASHING: toggles between
OFF state and ON state.
The flashing rate (1 Hz) is based on a timer capacitor
(CTIMER) of 0.1 µF. The rate varies based on the value
of the timer capacitor.
5.2.1.1 MCP73853 Only
STAT1 is on whenever the input voltage is above the
under voltage lockout, the device is enabled, and all
conditions are normal.
During a fault condition, the STAT1 status output is off
and the STAT2 status output flashes. To recover from a
fault condition, the input voltage must be removed and
then reapplied, or the enable input, EN, must be deas-
serted to a logic low, then asserted to a logic high.
When the voltage on the THERM input is outside the
preset window, the charge cycle will either not start or
be suspended. However, the charge cycle is not termi-
nated, with recovery being automatic. The charge cycle
resumes (or starts) once the THERM input is valid and
all other qualification parameters are met.
5.2.2
VSET INPUT
The VSET input selects the regulated output voltage of
the MCP7385X devices. With VSET tied to VSS, the
MCP7385X devices regulate to 4.1V. With VSET tied to
VDD, the MCP7385X devices regulate to 4.2V.
5.2.3 LOGIC ENABLE (EN)
The logic enable input pin (EN) can be used to termi-
nate a charge anytime during the charge cycle, initiate
a charge cycle or initiate a recharge cycle.
Applying a logic high input signal to the EN pin, or tying
it to the input source, enables the device. Applying a
logic low input signal disables the device and termi-
nates a charge cycle. When disabled, the device’s
supply current is reduced to 0.28 µA, typically.
DS21915C-page 16
2004-2013 Microchip Technology Inc.
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